docs: def parse_string_expr(self, string_expr_node):
          """ Parse a string node content. """
          string_expr_node_value = string_expr_node['value']
          string_expr_str = string_expr_node_value[1:-1]
  
          # Care escaped string literals
          if string_expr_node_value[0] == "'":
              string_expr_str = string_expr_str.replace("''", "'")
          else:
              string_expr_str = string_expr_str.replace('\\"', '"')
  
          # NOTE: This is a hack to parse expr1. See :help expr1
          raw_ast = self.parse_string('echo ' + string_expr_str)
  
          # We need the left node of ECHO node
          parsed_string_expr_nodes = raw_ast['body'][0]['list']
  
          start_pos = string_expr_node['pos']
  
          def adjust_position(node):
              pos = node['pos']
  
              # Care 1-based index and the length of "echo ".
              pos['col'] += start_pos['col'] - 1 - 5
  
              # Care the length of "echo ".
              pos['i'] += start_pos['i'] - 5
  
              # Care 1-based index
              pos['lnum'] += start_pos['lnum'] - 1
  
          for parsed_string_expr_node in parsed_string_expr_nodes:
              traverse(parsed_string_expr_node, on_enter=adjust_position)
  
          return parsed_string_expr_nodes